#71  
Old 01-11-2019, 11:13 PM
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mcodyclapp mcodyclapp is offline
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Originally Posted by jjmiller View Post
Do you believe that a disc generates lift great enough to overcome its weight? Not talking air bounces from wind getting under it. In absolute zero wind, I'd bet money that a disc never rises unless thrown upwards.



Just as a "rising fastball" is a myth in that a spinning baseball can slow its descent, but a human cannot generate enough spin/velocity to overcome the weight of the ball and make it actually "rise" in its flight.









Then why do golf balls have dimples?
Dimples are by design, on a spherical object that does not have a wing creating aerodynamic forces.

When's the last time you saw an airplane with a wing that was intentionally textured? Look up skin friction drag. You want a wing to be a smooth as possible to reduce your drag. Claiming a damaged flight surface creates less drag than a new smooth one is ridiculous.

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  #72  
Old 01-12-2019, 12:34 AM
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Originally Posted by Mocheez View Post
I am saying there are more physics that factor into the flight of the disc beyond the drag coefficient.

A Judge generates a lot more lift than a Firebird. I would have to reduce velocity in order to keep the Judge from lifting above 8 feet.
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Originally Posted by BENFTS View Post
The shape of the Firebird wing certainly generates more lift than that of a Judge.

You don't need to reduce velocity on your Judge, you just need to manage your release angle more effectively. Hit the field and shoot some video of that Judge going further than the Firebird....I'd love to see it.
You are both right and wrong, it depends on the conditions. The drag coefficient changes throughout flight and is dependent on a number things including speed, AoA, surface roughness, profile.
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  #73  
Old 01-12-2019, 01:18 AM
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Originally Posted by Mocheez View Post
I will pass on making videos. Maybe a better example would be a beat firebird vs. a fresh firebird. Which would go farther? Drag coeffiecient would be the same or maybe slightly less for the fresh firebird. But a beat firebird would have a little more turn/glide and fly farther.
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Originally Posted by BENFTS View Post
Over the course of beating in a disc the wing shape changes and can potentially reduced the DC of the seasoned disc. The flashing on the bottom of the wing is removed overtime from grinding on the ground and the wing bent downwards from multiple impacts with trees and earth. While a new Firebird might appear to have a lower DC the reality may be that the seasoned Firebird does. Removing the flashing at the bottom of the wing (the case with a beat Firebird) will actually reduce the DC and allow the disc to fly further with the same amount of energy imparted into the throw.
This largely depends on the speed and Reynold's number which also changes throughout flight.

I think when the Cd is lower on the beat up FB it has more to do with the wing getting beat up creating a turbulent boundary layer and acting as vortex generators and reduces drag. I've not noticed the wing tip being bent down on discs, it seems to largely maintain the same profile but significantly change the surface roughness.

New vs Old Firebird: https://www.youtube.com/watch?v=EaJTv8wUepA&t=2m21s


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  #74  
Old 01-12-2019, 01:24 AM
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Quote:
Originally Posted by mcodyclapp View Post
Dimples are by design, on a spherical object that does not have a wing creating aerodynamic forces.

When's the last time you saw an airplane with a wing that was intentionally textured? Look up skin friction drag. You want a wing to be a smooth as possible to reduce your drag. Claiming a damaged flight surface creates less drag than a new smooth one is ridiculous.

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Race cars have used rough textures for decades to reduce drag. Wings on airplanes are more complex, but they also are starting to get textures on some of the surfaces ( to increase lift)
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  #75  
Old 01-12-2019, 01:48 AM
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Originally Posted by jjmiller View Post
Do you believe that a disc generates lift great enough to overcome its weight? Not talking air bounces from wind getting under it. In absolute zero wind, I'd bet money that a disc never rises unless thrown upwards.

Just as a "rising fastball" is a myth in that a spinning baseball can slow its descent, but a human cannot generate enough spin/velocity to overcome the weight of the ball and make it actually "rise" in its flight.
I'll take that bet as well. A disc thrown on a downward trajectory with the nose up can rise due to lift - this is aka an air bounce and has nothing to do with "wind speed", but Angle of Attack(AoA). I can throw a disc upward that will go into negative lift or positive lift or zero lift.

The "rising fastball" does produce more Magnus lift than a sinker. But this argument has nothing to do with a disc producing lift via spin in the vertical plane which is due to speed and wing shape and AoA, although it does in the horizontal plane as that is the axis of spin on a disc, but would relate to a cutter rather than fastball.

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  #76  
Old 01-12-2019, 02:11 AM
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Originally Posted by mcodyclapp View Post
When's the last time you saw an airplane with a wing that was intentionally textured? Look up skin friction drag. You want a wing to be a smooth as possible to reduce your drag. Claiming a damaged flight surface creates less drag than a new smooth one is ridiculous.
Airplanes also typically fly at much higher speeds and bigger ranges of speeds, but in the same flow regime and Re this drag crisis effect would cause loss of stability/control, so efficiency is compromised for safety reasons.

A golf disc doesn't doesn't really have aerodynamic stability, all discs are understable and will flip over without a secondary stabilizing wing or spin, but since we do spin discs, it does has gyroscopic stability.

Gliders which fly closer to disc speed have used wing surface roughness to increase L/D ratio much like bird feathers.

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  #77  
Old 01-12-2019, 04:12 AM
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I don't feel like the effects of engineered-by-design homogenously textured surfaces can be compared to a surface that is marred with imperfections. There is a big difference between the actual surface of a wing/airfoil/etc having a texture vs a large percentage of a surface not being uniform. Think 8000 grit sandpaper vs 60 grit. Yes, the 8000 is technically textured, but it is uniform unlike the 60.

If the entirety of the wing was uniformly rough/textured it would make sense but a collection of uneven knicks, gouges, and likely uneven rim/wing thickness due to wear from the disc striking objects at different angles isn't assisting the aerodynamics.

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Old 01-12-2019, 04:13 AM
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Also look at scale. If you took the rough wing of a glider and scaled it down to disc size, that rough texture would likely be imperceptible to the human hand.

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Old 01-12-2019, 04:32 AM
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Originally Posted by mcodyclapp View Post
I don't feel like the effects of engineered-by-design homogenously textured surfaces can be compared to a surface that is marred with imperfections. There is a big difference between the actual surface of a wing/airfoil/etc having a texture vs a large percentage of a surface not being uniform. Think 8000 grit sandpaper vs 60 grit. Yes, the 8000 is technically textured, but it is uniform unlike the 60.

If the entirety of the wing was uniformly rough/textured it would make sense but a collection of uneven knicks, gouges, and likely uneven rim/wing thickness due to wear from the disc striking objects at different angles isn't assisting the aerodynamics.

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A disc is spinning unlike an aircraft, so imperfections of the wing tips largely balance out. Even in the old days of ball golf before dimples, the older non-uniform beat up balls flew further than new smooth balls.
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  #80  
Old 01-12-2019, 04:35 AM
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Also look at scale. If you took the rough wing of a glider and scaled it down to disc size, that rough texture would likely be imperceptible to the human hand.

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Aerodynamics change with scale size.
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